public HistoryItem Record(IDataModel model) {
			var item = new HistoryItem(model);
			var newNode = new HistoryNode(item);
			if (current != null) {
				current.Next = newNode;
				newNode.Previous = current;
			}
			current = newNode;
			return item;
		}
			public HistoryNode(HistoryItem item) {
				Item = item;
			}
 public HistoryNode(HistoryItem item)
 {
     Item = item;
 }